Outcomes associated with phosphorus binders in men with non-dialysis-dependent CKD

Oral activated charcoal suppresses hyperphosphataemia in haemodialysis patients

AIM

Hyperphosphataemia is almost inevitable in end stage renal disease (ESRD) patients and is associated with increased morbidity and mortality. In this study we examined whether oral activated charcoal (oAC) reduces serum phosphate level in haemodialysis patients.

METHODS

This was an open-label, prospective, uncontrolled study. One hundred and thirty-five haemodialysis patients were included in this study, with cessation of treatment with any phosphate binders during a 2 week washout period. Patients with serum phosphate levels greater than 5.5 mg/dL during the washout period were included for treatment with oAC. oAC was started at a dose of 600 mg three times per day with meals and was administered for 24 weeks. oAC dose was titrated up during the 24 week period to achieve phosphate control (3.5-5.5 mg/dL). A second 2 week washout period followed the end of oAC treatment.

RESULTS

In the 114 patients who successfully completed the trial, the mean dose of activated charcoal was 3190 ± 806 mg/day. oAC reduced mean phosphate levels to below 5.5 mg/dL, with mean decreases of 2.60 ± 0.11 mg/dL (P < 0.01) and 103 (90.4%) of the patients reached the phosphate target. After the second washout period the phosphate levels increased to 7.50 ± 1.03 mg/dL (P < 0.01). Serum intact parathyroid hormone (iPTH) levels declined from 338.75 ± 147.77 pg/mL to 276.51 ± 127.82 pg/mL (P < 0.05) during the study. oAC had no influence on serum prealbumin, total cholesterol, triglycerides, serum ferritin, haemoglobin or platelet levels and the levels of 1,25-dihydroxyvitamin D were stable during the study.

CONCLUSION

In this open-label uncontrolled study, oAC effectively controls hyperphosphataemia and hyperparathyroidism in haemodialysis patients. The safety and efficacy of oAC needs to be assessed in a randomized controlled trial.

Phosphate binder use and mortality among hemodialysis patients in the Dialysis Outcomes and Practice Patterns Study (DOPPS): evaluation of possible confounding by nutritional status

BACKGROUND

Poor nutritional status and both hyper- and hypophosphatemia are associated with increased mortality in maintenance hemodialysis (HD) patients. We assessed associations of phosphate binder prescription with survival and indicators of nutritional status in maintenance HD patients.

STUDY DESIGN

Prospective cohort study (DOPPS [Dialysis Outcomes and Practice Patterns Study]), 1996-2008.

SETTING & PARTICIPANTS

23,898 maintenance HD patients at 923 facilities in 12 countries.

PREDICTORS

Patient-level phosphate binder prescription and case-mix-adjusted facility percentage of phosphate binder prescription using an instrumental-variable analysis.

OUTCOME

All-cause mortality.

RESULTS

Overall, 88% of patients were prescribed phosphate binders. Distributions of age, comorbid conditions, and other characteristics showed small differences between facilities with higher and lower percentages of phosphate binder prescription. Patient-level phosphate binder prescription was associated strongly at baseline with indicators of better nutrition, ie, higher values for serum creatinine, albumin, normalized protein catabolic rate, and body mass index and absence of cachectic appearance. Overall, patients prescribed phosphate binders had 25% lower mortality (HR, 0.75; 95% CI, 0.68-0.83) when adjusted for serum phosphorus level and other covariates; further adjustment for nutritional indicators attenuated this association (HR, 0.88; 95% CI, 0.80-0.97). However, this inverse association was observed for only patients with serum phosphorus levels ≥3.5 mg/dL. In the instrumental-variable analysis, case-mix-adjusted facility percentage of phosphate binder prescription (range, 23%-100%) was associated positively with better nutritional status and inversely with mortality (HR for 10% more phosphate binders, 0.93; 95% CI, 0.89-0.96). Further adjustment for nutritional indicators reduced this association to an HR of 0.95 (95% CI, 0.92-0.99).

LIMITATIONS

Results were based on phosphate binder prescription; phosphate binder and nutritional data were cross-sectional; dietary restriction was not assessed; observational design limits causal inference due to possible residual confounding.

CONCLUSIONS

Longer survival and better nutritional status were observed for maintenance HD patients prescribed phosphate binders and in facilities with a greater percentage of phosphate binder prescription. Understanding the mechanisms for explaining this effect and ruling out possible residual confounding require additional research.

Calcium balance in normal individuals and in patients with chronic kidney disease on low- and high-calcium diets

Calcium balance in chronic kidney disease is poorly understood since its deficiency is a stimulus for secondary hyperparathyroidism and consequent bone loss while calcium excess promotes extra-osseous calcifications. To help resolve this, we evaluated calcium balance in normal individuals and in patients with chronic kidney disease (CKD) on daily diets containing 800 and 2000 mg elemental calcium. Both normal individuals and patients with late stage 3 and stage 4 CKD were in slightly negative to neutral calcium balance on the 800 mg calcium diet. Normal individuals were in modest positive calcium balance on the 2000 mg diet while patients with CKD on the same diet were in marked positive calcium balance at least over the 9 days of study; and significantly greater than the normal individuals. Increased calcium intake significantly decreased 1,25 dihydroxy-vitamin D and intact parathyroid hormone levels but did not alter the serum calcium concentration. Thus, our finding have important implications for both preventing calcium deficiency and loading in individuals with late stage 3 and stage 4 CKD.

Association of pretransplant serum phosphorus with posttransplant outcomes

BACKGROUND AND OBJECTIVES

Serum phosphorus levels are associated with mortality, cardiovascular disease, and renal function loss in individuals with and without chronic kidney disease. The association of pretransplant serum phosphorus levels with transplant outcomes is not clear.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data of the Scientific Registry of Transplant Recipients (SRTR) up to June 2007 were linked to the database (2001 through 2006) of one of the U.S.-based large dialysis organizations (DaVita). The selected 9384 primary kidney recipients were divided into five groups according to pretransplant serum phosphorus levels (mg/dl): <3.5, 3.5 to <5.5 (reference group), 5.5 to <7.5, 7.5 to <9.5, and ≥9.5. Unadjusted and multivariate adjusted risks for transplant outcomes were compared.

RESULTS

Patients were 48 ± 14 years old and included 37% women and 27% African Americans. After multivariate adjustment, all-cause and cardiovascular death hazard ratios were 2.44 (95% confidence interval: 1.28 to 4.65) and 3.63 (1.13 to 11.64), respectively, in recipients in the ≥9.5 group; allograft loss hazard ratios were 1.42 (1.04 to 1.95) and 2.36 (1.33 to 4.17) in recipients with 7.5 to >9.5 and ≥9.5, respectively. No significant association with delayed graft function was found.

CONCLUSIONS

Pretransplant phosphorus levels 7.5 to <9.5 mg/dl and ≥9.5 mg/dl were associated with increased risk of functional graft failure and increased risk of all-cause and cardiovascular deaths, respectively, when compared with 3.5 to <5.5 mg/dl. Additional studies are needed to examine whether more aggressive control of pretransplant serum phosphorus may improve posttransplant outcomes.

Dietary phosphorus intake and mortality in moderate chronic kidney disease: NHANES III

BACKGROUND

Dietary phosphorus intake is usually restricted in dialysis patients but the associations of dietary phosphorus intake with mortality in moderate chronic kidney disease (CKD) are unknown. Therefore, we examined these associations in National Health and Nutrition Examination Survey III.

METHODS

Dietary phosphorus intake was estimated from 24-h dietary recalls administered by trained personnel. CKD was defined as estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m(2). Time to mortality was examined by Cox regression models taking into account the complex survey design.

RESULTS

1105 adults with CKD were studied. Phosphorus intake was 1033 ± 482 mg/day (mean ± SD), eGFR was 49.3 ± 9.5 mL/min/1.73 m(2) and serum phosphorus was 3.5 ± 0.5 mg/dL. Compared to those in the lowest tertile of phosphorus intake (mean 532 ± 161 mg/day), those in the highest third (1478 ± 378 mg/day) had similar serum phosphorus levels (3.6 ± 0.5 versus 3.5 ± 0.6 mg/dL, P = 0.113) and modestly higher eGFR (50.0 ± 8.1 versus 47.5 ± 12.0 mL/min/1.73 m(2), P = 0.014). After adjustment for demographics, comorbidity, eGFR, physical activity, energy intake and nutritional variables, phosphorus intake was not associated with mortality [hazard ratio (HR) 0.98 per 100 mg/dL increase, 0.93-1.03].

CONCLUSIONS

High dietary phosphorus intake is not associated with increased mortality in moderate CKD, presumably because serum phosphorus levels are maintained in the normal range at this level of GFR. Interventional trials are needed to define optimal phosphorus intake in moderate CKD.

Diets and enteral supplements for improving outcomes in chronic kidney disease

Protein-energy wasting (PEW), which is manifested by low serum levels of albumin or prealbumin, sarcopenia and weight loss, is one of the strongest predictors of mortality in patients with chronic kidney disease (CKD). Although PEW might be engendered by non-nutritional conditions, such as inflammation or other comorbidities, the question of causality does not refute the effectiveness of dietary interventions and nutritional support in improving outcomes in patients with CKD. The literature indicates that PEW can be mitigated or corrected with an appropriate diet and enteral nutritional support that targets dietary protein intake. In-center meals or oral supplements provided during dialysis therapy are feasible and inexpensive interventions that might improve survival and quality of life in patients with CKD. Dietary requirements and enteral nutritional support must also be considered in patients with CKD and diabetes mellitus, in patients undergoing peritoneal dialysis, renal transplant recipients, and in children with CKD. Adjunctive pharmacological therapies, such as appetite stimulants, anabolic hormones, and antioxidative or anti-inflammatory agents, might augment dietary interventions. Intraperitoneal or intradialytic parenteral nutrition should be considered for patients with PEW whenever enteral interventions are not possible or are ineffective. Controlled trials are needed to better assess the effectiveness of in-center meals and oral supplements.

Clinical efficacy and cost-effectiveness of lanthanum carbonate as second-line therapy in hemodialysis patients in Japan

BACKGROUND AND OBJECTIVES

Lanthanum carbonate (LC) is a nonaluminum, noncalcium phosphate binder that is effective for hyperphosphatemia in dialysis patients. However, its efficacy and cost-effectiveness as second-line therapy have not been fully examined.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We first conducted a multicenter, open-label, 16-week clinical trial to examine the effect of additive LC in 116 hemodialysis patients who had uncontrolled hyperphosphatemia with conventional phosphorus-lowering therapy alone. Based on these clinical data, a state transition model was developed to evaluate the benefits and costs associated with LC as second-line therapy. Reduced risks for cardiovascular morbidity and mortality among patients treated with LC arise through more of the population achieving the target phosphorus levels. Uncertainty was explored through sensitivity analysis.

RESULTS

After 16 weeks of additive LC treatment, mean serum phosphorus levels decreased from 7.30 ± 0.90 to 5.71 ± 1.32 mg/dl, without significant changes in serum calcium or intact parathyroid hormone levels. A subsequent cost-effectiveness analysis showed that compared with conventional treatment, additive LC incurred an average additional lifetime cost of $22,054 per person and conferred an additional 0.632 quality-adjusted life years (QALYs). This resulted in an incremental cost-effectiveness ratio of $34,896 per QALY gained. Applying a cost-effectiveness threshold of $50,000 per QALY, a probabilistic sensitivity analysis showed that additive LC had a 97.4% probability of being cost-effective compared with conventional treatment.

CONCLUSIONS

Our results indicate that the use of LC as second-line therapy would be cost-effective among hemodialysis patients with uncontrolled hyperphosphatemia in Japan.